Process and installation for the distribution, into a mold, by high speed projection, of a granular and/or pulverulent mixture

ABSTRACT

A process and apparatus are provided for mixing and distributing a pulverulant mixture wherein the ingredients of the mixture are mixed in a mixing zone, the mixture is then passed to a distribution zone and the mixture is passed from the distribution zone to a point of utilization by applying thereto an expanded compressed gas current while preventing the return of the mixture to the mixing zone.

United States atent [1 1 Richard Oct. 14, 1975 [54] PROCESS AND INSTALLATION FOR THE 998,762 7/1911 Faller 259/1 51 DISTRIBUTION, INTO A MOLD, BY G 2,983,489 5/1961 Unland .1 259/151 X 3,194,539 7/1965 Hanne-Wiame 259/151 X SPEED PROJECTION OF A GRANULAR 3,346,239 10/1967 Larson 259 9 AND/ OR PULVERULENT NHXTURE Gerard Yves Richard, 30, rue du Havre, 60 Precy-sur-Oise, France Filed: May 29, 1973 Appl. No.: 364,613

Inventor:

Foreign Application Priority Data May 29, 1972 France 72.19176 References Cited UNITED STATES PATENTS 5/191 1 Babcock 302/51 Primary ExaminerPeter Feldman Assistant Examiner-Alan Cantor Attorney, Agent, or FirmJohnston, Keil, Thompson & Shurtleff [5 7] ABSTRACT A process and apparatus are provided for mixing and distributing a pulverulant mixture wherein the ingredients of the mixture are mixed in a mixing zone, the mixture is then passed to a distribution zone and the mixture is passed from the distribution zone to a point of utilization by applying thereto an expanded compressed gas eurrent while preventing the return of the mixture to the mixing zone.

10 Claims, 10 Drawing Figures US. Patent Oct. 14, 1975' SheetlofS 3,912,238

US. Patent Oct. 14,1975' Sheet 3 of5 3,912,238

US. Patent Oct. 14, 1975 Sheet 4 of5 3 912 238 2% Q as US. Patent Oct. 14,1975 Sheet50f5 3,912,238

PROCESS AND INSTALLATION FOR THE DISTRIBUTION, INTO A MOLD, BY HIGH SPEED PROJECTION, OF A GRANULAR AND/OR PULVERULENT NIIXTURE The present invention relates to a process and to an installation for the distribution into a mold, by high speed projection, of a granular and/or pulverulent mixture especially composed of a foundry sand and of a binding-hardening system, the distribution of such a mixture being done from a mixing chamber, in which said mixture is formed in the course of an initial step, to the point of utilization of said mixture. The invention also relates to a pneumatic accelerator of the particles of the mixture, granular and/or pulverulent, which makes possible their projection to the inside of a mold.

The present invention of course, applies to all sandbinding agent-hardening agent mixtures, but it is obvious that it is more particularly meant for the distribution of quick-setting or instantly setting mixtures. It is evident that the present invention also applies to the distribution of mixtures obtained according to processes which are approximately similar, in industries close to foundry, for example, to the distribution of mixtures which mostly include a refractory product, or a marble aggregate agglomerated to a resin to form a synthetic marble.

At present, in the foundry field, more and more sandbinding agent-hardening agent mixtures are used which set rapidly or almost instantly. Consequently, it is necessary for the mixers on each side of the apparatus for taking and distributing the mixture to its point of utilization, to be short length apparatus, or even apparatus inside which the displacements of the mixture are themselves ultra rapid.

With respect to mixers, it has already been suggested to juxtapose main and secondary apparatus inside each one of which there is formed a non-active fraction of the mixture (sand and binding agent on one side, sand hardening agent on the other) before uniting all of the non-active fractions of the mixture to constitute, in a point as close as possible to its location of utilization, a mixture which at this time has become active and is ready to be hardened.

With respect to apparatus for taking and distributing the mixture, there is in practice, today, two well known conveying devices for the mixed refractory mass. In the first device, the mixed mass runs through a bufferhopper from the mixing chamber to the point of utilization of the mixture, through one or several fixed or articulated conveyor belts. At times, the last conveyor belt has at its end a turbine to violently project the mixture from top to bottom inside the molding imprint.

In the second device, more recent in conception, the basic materials to be mixed are brought into a mixing screw mixer which works at the same time as a mixer and as a conveyor. Variations in that device provide for, either several mixing screws in a series, or an intake of the basic materials to be mixed by conveyor belts to a final mixing screw which distributes the mixed mass directly at a point of utilization. Each mixing screw, each conveyor belt, constitutes an arm the first end of which pivots on a rotating plate and the second end of which either pivots on another plate in the case when said am is in intermediary in the installation, or which releases the mixture and lets it flow by gravity, to fill in continuous molding imprints.

French Pat. No. 1,335,806, and British Pat. Nos. 987,488 and 987,490, in various forms describe embodiments of this second type of device.

Variations of those two known types of devices for the taking and the distributing of a mixture may be considered by replacing each belt conveyor by any other type of known conveyor, such as a vibrating corridor, an air-slide, etc.

The advantage of the first distribution device by conveyor after mixing resides in the fact that its field of action is practically limitless, since it is sufficient to modify the articulations between the various conveyors, or also to add additional conveyors at the end of the last existing one, to reach any point of a new installation. However, taking into account modern technology which more and more makes use of self-hardening mixing masses with fast setting, said first device tends to be abandoned, at least with respect to conventional conveyor belts, flat and with a low displacement speed, because the mixed mass shows a tendency to harden on the conveyor belts and to lose its qualities, thus giving, after hardening, a final product with poor mechanical characteristics, with the incorporation of elements which have already hardened on the belt, thus creating weak points in the molded mass and, consequently, for said molded mass, very heterogeneous final physical characteristics. Consequently, only high speed conveyor belts, and especially those placed inside a tubular corridor, remain usable for the distribution of fast setting mixtures. However, in all cases, the arrangement which makes use of a turbine placed at the end of the last belt presents a serious drawback resulting from the fact that the turbine becomes clogged very rapidly. Such an arrangement, therefore, has been abandoned in practice, and at the end of the last belt the mixture is always poured by simple gravity, that is to say, it reaches the mold at a very low speed.

The second type of distribution device, which consists in using the mixer itself as a conveyor arm, of course solves part of the drawback presented above. On the other hand, said type rapidly reaches its own limits because of the complex construction such a system requires when it must cover an important surface, in other words, when it is desired for the mixing arm or arms to have a large field of action.

There are also known devices which insure the pneumatic transportation of granular or pulverulent products, of foundry sands, for example. Such devices, especially described in British Pat. No. 805,956, and in Belgian Pat. No. 362,015, have as their essentialrole, but a limited one, to insure transportation of product particles from one point to another, the particles entering a gas current under pressure, at some speed, a practically inconsequential speed in general, and being taken to a storage zone where the particles are deposited, their speed of arrival immediately preceding their immobilization having, in all cases, no significance. In other words, a pneumatic conveyor takes solid particles from one point and displaces them at a more or less significant speed to take them to a second point and to deposit them so that they will be stored for the purpose of their coming utilization. In the course of the pneumatic transporation properly speaking, the speed of the solid particles may be very high, but no particular precaution is taken at the time when they are going to be deposited by the gas current under pressure, since the problem is a simple release of the particles for the purpose of the temporary storage, and not for their immediate utilization.

Moreover, in all cases, such pneumatic conveyors include, downstream from the transportation duct, a hopper for the unloading of the particles, and upstream from the duct, a storage chamber. The hopper constitutes a first chamber inside which the mixture either is stored, or from which it is poured into the duct, pouring in this latter case being of necessity carried out at low speed. The storage chamber includes an opening facing which there opens the transportation duct and at least one second opening for taking back the particles which have been temporarily stored in said chamber, the second opening being to that end closed by movable shutters. Thus, the pneumatic conveyor of necessity includes two zones, respectively, downstream and upstream from the duct, at the level of which the particles to be transported are in all cases stored for a given period of time, and then said particles being given a low speed generated by the fall by simple gravity of the particles for the purpose of their being taken back by the current of gas under pressure for one thing, and their being led to the point of utilization for the other. As a conclusion, pneumatic conveyors cannot be used as such for the transportation of a foundry mixture which sets rapidly, from a mixing device in which the mixing takes place, to the point of use of said mixture, for invariably there would occur sticking phenomena, as well as more or less complete hardening phenomena of the mixture prior to the utilization of same. Thus, there are found again the drawbacks presented with respect to the first type of distribution device indicated above.

The present invention has as its purpose to remedy the aforementioned drawbacks and, to that end, it has as its object a process for the distribution of a mixture by projection, at high speed, from the mixing chamber to the point of utilization of said mixture, which is easier in execution, which is rapid and which advantageously makes possible an instantaneous distribution of the mixture at any point of the installation, which, of course, has been chosen in advance. Said process, which combines the advantages of the two aforementioned devices (unlimited field of action of the first one, instantaneous distribution of the second one) while eliminating the whole of their drawbacks, is, therefore, a process highly flexible, in its utilization.

The present invention also has as its object a distribution installation which includes, at the outlet of a classical continuous or discontinuous mixer, devices for the transportation of the mixture to its point of utilization which are very simple in execution and in their operation. It finally has as its object a pneumatic accelerator which constitutes the main device insuring the projection of the mixture at a very high speed to the point of utilization of said mixture.

According to the invention, a process is provided for the distribution as far as its point of utilization, by high speed projection, of a granular and/or pulverulent mixture which includes, for example, a refractory product of the foundry sand type and a binding-agenthardening-agent system, or even marble aggregates and a resin, said mixture being more especially of the fast setting type or of the type which sets almost instantly, said process including the initial phase of formation of the mixture in a mixing chamber, which is characterized by the fact that said mixture is moved from the mixing chamber to its point of utilization inside a pneumatic accelerator which prevents the reflux of the mixture, and in that said mixture is set into motion using the expansion of a compressed gas, so as to insure pneumatic transportation of the mixture from the in side of the accelerator to its point of utilization.

In one preferred embodiment, the mixture is displaced by simple gravity, inside the pneumatic accelerator, until it is taken back by the compressed gas current. There is blown into the pneumatic accelerator a current of compressed gas which serves as the mixtures high speed transportation agent, forming a ringshaped jet converging toward the outlet of said accelerator, and said mixture to be transported is introduced approximately at the center of said jet which is ringshaped. The movement of the mixture is accelerated by using the expansion of the compressed gas acting on the speed of reaction of the setting of said mixture, either through a modification of the compressed gas, or by adding to it an auxiliary agent which can react with respect to the mixture.

A distribution installation, up to its point of utilization by high speed projection, of a granular and/or pulverulent mixture, said installation including a mixing device for the formation of the mixture and means for picking up said mixture at the exit of the mixing device, and for its distribution up to its point of utilization, is characterized by the fact that it includes: a pneumatic accelerator which communicates on one side with the exit of the mixing device and on the other side with the point of utilization of said mixture; means for displacing said mixture inside said pneumatic accelerator, from the exit of the mixing device to the exit, approximately of said pneumatic accelerator; means for the pneumatic setting into motion of the mixture from approximately the exit of said pneumatic accelerator to its point of utilization; internal means in the pneumatic accelerator, to prevent any reflux of the mixture from said accelerator toward the mixing device, optionally a tubular duct for the distribution of the mixture connecting the exit of the pneumatic accelerator to the point of utilization of the mixture.

In a first embodiment, the pneumatic accelerator includes a body which communicates with the exit of the mixing device and fitted with a venturi-shaped sleeve, in two parts: one internal part and one external part placed so that the widened zone of the venturi is placed facing the outlet of the mixing device, and so that the narrowing of the venturi is placed facing the utilization or, possibly the intake point of the duct of distribution, a radial channel running through the body and the external part of the venturi establishing communication between a source of gas under pressure and a ringshaped expansion chamber, cylindrical then in the shape of a truncated cone the wall of which is convergent toward the exit of the pneumatic accelerator, said chamber being located between the internal and external parts of the venturi-shaped sleeve, the internal part of said venturi and the head or intake of the distribution duct. The ringshaped expansion chamber has at least one rib with a helix-shaped thread, suitable to cause a whirlwind type motion of the gas current.

In a second embodiment, the pneumatic accelerator which includes a cylindrical body the axis of symmetry of which is vertical, the lower opening of which is placed facing the poing of utilization and the upper opening of which is facing the intake of the mixed mass distributed from the mixing devi'ce, said body serving as a guide for a slide member which slides in a passageway surmounted by a tube, said tube being bevelled in its lower part and forming a truncated cone Zone and said passageway presenting at its upper part a truncated cone shaped boring, the summit half angle of which is identical with that of the truncated cone shaped end of the tube, an opening running through the body in the transverse direction and opening into a cylindrical ringshaped chamber formed between the body on one side, the tube and a projection of the slide member on the other side, said chamber extending between the truncated cone shaped faces of the tube and of the slide member which face each other, in the form of a truncated cone shaped ringlike chamber, the wall of which converges toward the exit of the pneumatic accelerator. The play which exists between the truncated cone faces of the tube and of the slide member which face each other, and defining the truncated cone annular ring through which the conveyor gas under pressure is introduced into the central part of the pneumatic accelerator, is adjustable from the outside of said accelerator, for example, with the help of a maneuvering rod welded to the lateral wall of the slide member and running through the body at the level of a vent which is slanted with respect to the horizontal.

In one preferred embodiment, the annular chamber of the truncated cone shaped annular ring defined between the tube and the sliding member delivers a current of compressed gas, which serves as transporting agent for the mixture, at high speed, and forms a cone shaped annular jet converging toward the exit of the accelerator, said cone shaped jet having an angle eat its summit which is approximately equal to 30. Installation includes at least one secondary piping opening either on the inside of the pneumatic accelerator in any point of the distribution tubular duct, said secondary piping making possible the introduction into the gas current transporting the mixture of an auxiliary agent reactive with respect to said mixture.

As already specified, the pneumatic transportation in piping systems has already been known in various applications, especially in foundry work. In addition to the aforementioned patents, there is also German Pat. No. 1,172,012 which describes such a transportation device to bring the constituents of the mixture to the mixing device. However, it is clear that the purpose sought in the present invention is not specifically found in the transportation properly speaking, but in the speed and in the flexibility of use of the transportation of a mixture ready to harden. Pneumatic transportation consequently makes possible the introduction, into any point of utilization, of a still non-active mixture, a result which it is impossible to reach when using the present installations. With respect to the existing techniques, the main advantages of the present invention can therefore be summarized as follows:

a. the invention makes it possible to consider the transportation of mixed masses which set very rapidly," taking into account the high linear speed which may be reached in the piping systems.

b. the piping systems used, being very light, make it possible to reach fields of actions unknown until now with the already manufactured conveyor mixers. Moreover, the profile of those pneumatic piping systems may vary indefinitely, in length as well as in orientation, the latter possibly being flexible, or articulated either by means of rubber elements, or even by rotating joints which are tight and allow for even very closed angles. The piping systems can also be adjusted in height by means of a mechanical, hydraulic or pneumatic raising system.

0. while in the other installations known until now the mixed mass arrives at the end of the run by gravity, at the end of the present installation, said mixed mass arrives with still a very high pressure resulting from the gas current and at the speed generated in the pneumatic accelerator, a situation which makes it possible in all cases to make molded objects, without any necessity for either hand or mechanical shaking or vibrations. Therefore the work and the fatigue of the operator are appreciably decreased, and there is made possible a greatly improved productivity. Moreover, when variations are caused in the pressure of the pneumatic conveyor gas, it is possible to execute a compacting of the mixed mass with an adjustable force, making it possible, for example, to project said mixed mass first with a low pressure on the pattern, a situation which prolongs the durability of same, and then with a higher pressure, to insure maximum compacting.

d. the use of enclosed pneumatic transportation ducts for the distribution of the mixed mass makes possible a physical or chemical modification of the state of said mass being transported through the use of a nonneutral gas, either an accelerating or an inhibiting agent of the reaction, or even air, the gas or the air possibly being heated or cooled, or even through injection into the air of propulsion, either-wholly or in part, of a gas or of an aerosol which is to exert a chemical reaction on the mixed mass. Such a gas, is, for example, the vehicle of a liquid product, distributed in the form of fine droplets, active for a shorter or longer period of time on the mixture, e.g., a hardening agent, a catalyst, a reaction-retarding agent.

e. the pneumatic accelerator, which on the one hand communicates with the exit of the mixer, and on the other hand the side on which there is optionally branched a distribution piping system, may be fitted on any existing mixing system, either continuous or discontinuous, and it can bring to it a great flexibility of utilization as a result of the flexibility of the pneumatic distribution.

f. Finally, the distribution pipings usually used, being generally of small section, present a small volume and consequently can therefore always be empty at the end of the filling cycle of the molding imprints, or at the time of any stop. Said expulsion from a duct of all of the reactive mass or mass ready to harden, excludes all risks of hardening of the mixed mass prior to its use.

It is therefore certain that the process and the installation which are the objects of the present invention, insure, for one thing, a technical result different from the one obtained until now by means of known process or installation, and moreover, present industrial advantages which are not apparent with the use of the former techniques.

The following description which is not limitative, illustrates various embodiments of the present invention, with reference to the drawings in which:

FIG. 1 is a schematic view, in profile, of a first embodiment of an installation according to the invention, in which the pneumatic accelerator is a venturi;

FIG. 2 is a longitudinal axial section of the pneumatic accelerator of the installation in FIG. 1;

FIG. 3 is a schematic view, in profile, ofa second embodiment of the installation according to the present invention, in which the pneumatic accelerator of the venturi type, in FIG. 2, is preceded by a rotary chamber, placed at the exit ofa discontinuous mixing device;

FIG. 4 is a schematic representation of a modification in which the pneumatic accelerator of the venturi type seen in FIG. 2 is preceded by two alternating closing valves, placed at the exit of a mixing device which also is discontinuous;

FIG. 5 is a profile view of a complete installation composed of: the distribution members of the materials to be mixed, of a mixing device for the mixing of said materials of the pneumatic accelerator, in any form, and of a distribution piping system, with multiple articulations both in the vertical and in the horizontal plane;

FIG. 6 is a view from the top of the complete installation shown in FIG. 5;

FIG. 7 is a profile view of a third embodiment according to the present invention, composed of: articulated arms taking said sand, with the help of conveyor belts, up to a mixing device placed on the last articulated arm, said mixing device simultaneously receiving other constituents of the mixture such as the binding agent, the hardening agent, of a pneumatic accelerator which communicates with the exit of the mixing device and opening above the mold inside of which the mixture obtained must be introduced under high pressure;

FIG. 8 is a profile view of a fourth embodiment according to the present invention, said embodiment including going from upstream to downstream: members for the distribution of the materials to be mixed, as well as a mixing device for the mixing of said materials, a plurality of articulated arms, each one of them fitted with a system of transportation by belt, taking at very high speed the mixed mass to a pneumatic accelerator placed at the end of the last articulated arm, and projecting the mixture under very high pressure into the foundry mold;

FIG. 9 is a profile view of the pneumatic accelerator with adjustable gas delivery, used at the extreme part of the installation seen in FIGS. 7 and 8; and

FIG. 10 is a cross sectional view of the conveyor belt used in the installation in FIG. 8, said belt having its upper part placed inside a tubular duct, and its lower part, or return part, on the inside and below said duct.

With reference to FIGS. 1 to 6, a first embodiment according to the present invention includes, in the first place, for the formation of the mixture, any type of mixing device 1, either continuous or discontinuous, vertical or horizontal, fixed or movable, that is to say, for this latter case mounted on a rolling platform or suspended to a gallows-like support or portico, or even articulated around a vertical shaft on its support. From the exit 2 of the mixing device, the mixed mass which is ready to harden is distributed by a pneumatic accelerator 3, immediately followed by a distribution duct 4, above a molding imprint 5 into which it falls vertically in 6 with a certain force of projection which is adjustable as a function of the gas pressure used for the distribution of the mixture.

Pneumatic accelerator 3 communicates, on one side by its intake 3a with exit 2 of the mixing device 1 and v on the other side, by its outlet 3b with intake opening 7 of duct 4. The mixed mass is displaced inside said pneumatic accelerator, from the mixing device toward the duct, said pneumatic accelerator being constructed, moreover, in such a way that it prevents the reflux of the mixture from the duct toward the mixing device.

The displacement of the mixed mass inside accelerator 3 can be done by any known means. Preferably there is used for that displacement the natural vertical fall, by gravity, of the mixture from exit 2 of the mixing device where it was formed, to exit 3b of the accelerator where it is taken back and distributed.

Under the effect of shakings or of vibrations, or by means of simple aspiration (a vacuum created approximately at the exit of the accelerator by the passage of the gas used for the pneumatic transportation of the mixture up to its point of utilization), the displacement of the mixture inside the pneumatic accelerator this time taking place following a slanted path downward from the exit of the mixing device to the exit of the accelerator.

In a first embodiment, represented in FIGS. 1 and 2, of the pneumatic accelerator 3, the latter includes a body 9, cylindrical with a vertical axis of symmetry 10, provided in its hollowed central part with a vertical sleeve in two parts, an internal part 11 and an external part 12, said two parts of the sleeve being fixed one with respect to the other and secured at the upper part of body 9 by means of screws schematically represented by their fixation axis 13. The external part 12 of the sleeve is a cylindrical ring, the axis of symmetry of which is vertical and identical with axis 10. The internal part 11 of the sleeve is composed in its upper part of a cylindrical ring and its lower part of a truncated cone shaped ring with walls converging downward, the axes of symmetry of the cylindrical and truncated cone shaped rings being vertical and identical with axis 10. The external diameter of the cylindrical ring of internal part 11 is slightly less than the internal diameter of the cylindrical ring of the external part 12, so that there remains between said cylindrical rings a cylindrical annular chamber 15 the vertical axis of which is 10. A radial duct 14, approximately horizontal, running through body 9 then through the external part 12 of the sleeve, communicates on the one hand with a source of gas under pressure, connected by means of a piping system schematically represented by arrow 16 to a connection 14a mounted at the intake of duct 14, and on the other hand, at the level of its exit opening 14b, with annular expansion chamber 15.

The distribution duct 4 is formed in its initial part, at least at the level of its intake opening 7, by a head 17 movably mounted for rotation on body 9 by means of a conventional bearing system, Le, a bearing with cone shaped rollers, or a ring with balls, 18. Head 17 includes, especially, above intake opening 7 of the duct properly speaking, a cone shaped funnel 28 the axis of which is vertical. The walls of said funnel converge downward, the summit angle of the cone shaped funnel is equal to the summit angle of the truncated cone shaped ring of the internal part 1 l of the sleeve, and the funnel has a depth such that, when head 17 is mounted on body 9, there remains between said funnel and the external face of the truncated cone shaped ring of internal part 11 of the sleeve, a truncated cone shaped annular ring 19 with walls converging downward. The width of chamber 19 is approximately equal to the width of cylindrical chamber 15, so that the whole expansion chamber 15,19 of the gas under pressure, inside the pneumatic accelerator 3 has a uniform diameter. The diameter of duct 14 is sufficiently greater than the width of chambers 15,19, so that there will be practically no gas pressure drop between the gas pressure source and the intake 7 of duct 4.

Body 9 is fixed in the upper part, after inserting a seal 20, on a collar or flange 21 secured to mixing device 1. The fixation of body 9 on said collar 21 is done by means of screws or pins the position of which is, for example, fixed by axes 22. Seal and collar 21 have at their center a cylindrical opening, the diameter of which corresponds approximately to the internal diameter of internal part 11 of the sleeve.

From its exit from the mixing device, the granular and/or pulverulent mixture, composed, for example, of sand, of binding agent and of hardening agent, vertically falls into the accelerator, as indicated by arrow 8, inside the internal part 11 of the venturi-forming sleeve, then it is taken back in 3b at the exit of said accelerator by a current 23 of compressed gas which forms an annular jet directed downward and toward the axis of the piping system, that is to say, which converges toward intake opening 7 of duct 4 placed downstream from the accelerator. The mixture to be transported falling by simple gravity to the center of said annular jet, is of necessity taken back at the exit 3b of the accelerator by current 23 of gas under pressure, and directed to 24 toward the exit of the distribution piping system 4. The natural current 23 of compressed gas being directed downward, there is thus prevented any back up of the gas current, that is to say, any backflow of the sand from the exit 3b of the accelerator toward exit 2 of the mixing device, a backflow which would have a deleterious effect to hinder the regularity of the work inside the mixing chamber.

Advantageously, the expansion chamber 15,19 includes one or several ribs the thread of which is helixshaped, extending downward, said ribs having as their purpose to cause a whirlwind motion of the gas in the expansion chamber, a whirlwind motion which is preserved at the time the mixture is taken back at the intake point of the duct and during the displacement of said mixture through the duct, thus preventing any clogging of the latter.

The first embodiment of the accelerator is advantageous to the extent that sleeve 11,12 and head 17, cone shaped at 28, orient the distribution of the mixture in duct 4 without requiring any mechanical means. The only fragile member of said embodiment is ball bearing ring 18 but the latter, despite the slight play 25 which remains between the external part 12 of the sleeve and head 17 to make possible the free rotation of the latter, cannot be reached by any fraction of the mixture flowing back under the action of gas current 23, and consequently its dependability is insured.

Pneumatic accelerator 3 may be used as such, at the exit of any mixing device, either ccontinuous or discontinuous. However, in the particular case in which mixing device 1 is discontinuous, it is obvious that the mixed material will be poured intermittently into the pneumatic accelerator, and consequently the regular functioning of the latter might become affected. It is therefore particularly advantageous to place between exit 2 of a discontinuous mixing device and the intake point 3a of the venturi type pneumatic accelerator a member which insures a better distribution of the load of mixed materials which are introduced into said pneumatic accelerator.

In a first variation represented in FIG. 3, there is placed, between the exit of the discontinuous mixing device 1 and the intake point of the pneumatic accelerator 3, a rotary or an alveolar chamber. The inlet for compressed gas 27 is located at the level of the chamber compartment loaded with the mixture received from the mixing device. In all cases, the mixture is picked up by the current and distributed into mold 5 with the help of duct 4 placed at the exit of the pneumatic accelerator. Said arrangement however presents a certain drawback to the extent in which there may occur a more or less rapid clogging at the level of chamber 26.

Consequently, in a second embodiment represented in FIG. 4, the pneumatic accelerator 3 is placed downstream from two valves, an upper one 29 and a lower one 30, connected one to the other by means of a vertical cylindrical chamber 31. The upper valve 29 communicates in addition with exit 2 of the discontinuous mixing device 1, and the lower valve 30 directly opens on the intake point of the pneumatic accelerator.

Each one of these two valves has a deformable internal sleeve 29a and 30a respectively, the opening of one of the two valves and the simultaneous closing of the other are electro-pneumatically controlled in 32, by means of a four-way electro-valve, according to a predetermined rhythm which is of the order of a few seconds for the distribution of a product of the foundry sand type. The frequency of opening and of closing of each valve is a function of the useful volume of chamber 31 and of the rate of flow of mixing device 1.

When upper valve 29 opens, the lower valve 30 is closed and the mixed sand, which falls by gravity from exit 2 of mixing device, falls into chamber 31. Then, under the action of electropneumatic control 32, valve 29 closes, valve 30 simultaneously opens and lets the volume of said contained in the chamber flow by, that is to say, it lets it fall by gravity in 33 into the pneumatic accelerator 3, where it is taken up by a gas current 34 directed toward the place of distribution and of utilization of the sand by duct 4. FIG. 4 schematically gives the functioning of that variation in execution at the moment when upper valve 29 is closed and the lower valve 30 opens. The first embodiment of pneumatic accelerator 3 which has just been described, as well as its variations which consist in placing upstream from said accelerator, either a rotary chamber 26, or a couple of valves 29,30 with deformable internal sleeves, placed above each other, makes possible the fall continuously or discontinuously of the mixed sand, then the picking up of said sand by a gas current directed toward utilization, usually through a distribution duct. Each one of these three embodiments has an advantage-the fact that it prevents backflow of the sand, from down up, which might occur when exit 2 of mixing device 1 and exit 3b of the pneumatic accelerator are in communication. Said backflow would become concretized by transportation from bottom up, of a fraction of the mixed mass by a fraction of the gas current, and then the fraction of mixed mass would be pushed back inside mixing device 1 and it would undoubtedly exert a negative action on the useful end of the mixing device. It is therefore absolutely necessary for accelerator 3 to constitute a means of absolute insulation between mixing device 1, either continuously or discontinuously, and utilization in mold 5, from said utilization to said mixing device.

Two other advantages of the present invention, resulting from the use of pneumatic transportation for the mixed masses, and which are made possible by the particular embodiments which have been suggested, are the following:

By regulating the pressure of the compressed gas which is released at the level of the exit of the accelerator, it is possible to cause variations in the compacting pressure of the sand in the mold. Preferably, the mixture will be projected in said mold under a low pres sure at the beginning of the filling, and then under high pressure, for the purpose of insuring a maximum compacting inside said mold. Simultaneously, the extreme part of the installation, through which there flows under pressure jet 53 of mixture, is impressed with a motion 54 and to and fro above said mold, in order to further improve the evenness of the filling of said mold.

It is possible to introduce inside pneumatic accelerator 3 or inside duct 4, and in this latter case by means of a secondary piping 35, a gas or aerosol, which transports in the form of fine droplets which are dispersed, an accelerating or an inhibiting agent for the hardening reaction of the mixed mass. Said secondary piping will open at any point of the duct, either near its intake point (FIG. 2), or preferably near its exit point (FIG. 1) especially when the additional compound which is introduced into the duct 4 is an accelerator with a violent reaction on the transported mixture.

Each distribution piping 4, the essential character of which is to make possible a filling of molds by projection, which is possible with none of the devices known, consists either of rigid metal tubing or of rubberized flexible tubing. The diameter of each duct is suited to the flow required, its profile may include as many elbows or articulations as required. The pressure necessary for pneumatic transportation essentially is variable as a function of the form and of the density of the mass which is mixed, as well as of the rates of flow worked with. The low pressure systems using a 0.3 atmosphere gas, therefore, are as well suited as the high pressure systems reaching 7 or 8 atmospheres, and at times more. Moreover, each pneumatic transporation duct may be supported by a packing meant either to increase its rigidity or to improve its appearance, this without any alteration of the basic principles.

A complete pneumatic mixing and transporting installation is represented in FIGS. 5 and 6. The support for said installation consists of a rolling platform 36, the displacement of which is governed by a motor 37, and by a transmission 38 which acts on a set of motor wheels 39. The sand to be mixed is introduced from an intake box 40 into a storage hopper 41. The mixing constituents (for example, the resin and the hardening agent) are placed into containers 42 and 43, respec tively. From a control station with a control board 44 and optionally a monitoring television screen, the operator controls the introduction of the sand, of the resin, and of the hardening agent into mixing device 1. The resin and the hardening agent are pneumatically brought to mixing device 1, through a piping system 45, while the sand is raised from the bottom of hopper 41, by an elevator 46, then falls toward the intake point of the mixing device through a descending duct 47. From a group of compressors 48, there is sent to the lower part of pneumatic accelerator 3 a gas under pressure into duct 4 for picking up the mixture and for the distribution of samd into mold 5. Duct 4 is supported by a member 49 with multiple articulated arms, the last projecting arm 49a having, in addition, at the level of its projection head 50, a television camera 51 which makes it possible for the operator to watch the filling of said mold 5 while he may be several tens of meters away from the same.

The complete displacements of each arm of member 49 are, with respect to one another, in a horizontal plane, of the order of 240 for angle a which corresponds to the complete displacement of the first arm with respect to the support, and 280 for angle B which corresponds to the complete displacement of projecting arm 49a with respect to the arm which procedes it. A mechanical, hydraulic or pneumatic jack 52, affixed on one side by its end 52a to the support of mixing device 1, of the intermediary part and of the pumping compartment, and on the other side by its end 52b to the first arm of member 49, makes possible the adjustment in height of projection arm 49a.

The first embodiments of the installation according to FIGS. 1 to 6 include, whether the accelerator 3 is used alone or preceded by a temporary holding device, a distribution duct formed by a tubular duct which allows the pneumatic transportation of the mixture from the exit of the pneumatic accelerator to the point of utilization. It is evident, however, that the connection between the exit of the pneumatic accelerator and the uti lization point may be obtained by means of other devices, two main variations of which are represented in FIGS. 7 and 8.

The third complete embodiment for the mixing and high speed distribution of the mixture, represented in FIG. 7, especially includes a hopper 55 inside which there is introduced sand, as schematically represented by arrow 55a. Said sand flows by gravity inside a vertical duct 57, then it is taken up by a first conveyor belt 58 moving at high speed inside a tubular duct 59. Said conveyor belt is advantageously placed inside a carrier which consists of a first arm extended by a second arm, the carrier 60a of which encloses a second belt 58a also provided with a very rapid displacement motion inside a tubular duct 59a. Deflections 61 and 61a, respectively, are placed at the ends of the first and of the second arm and take the mixture, respectively, from the first to the second arm and from the second arm to a mixing chamber 1 which in reality constitutes the third arm of said installation. Of course, elements 60, 60a and 1 of that installation or embodiment are movable in the horizontal plane, with respect to one another, so that the position occupied by exit 2 of the mixer may be directed at the right angle of any point of use, schematically represented by mold 5 in FIG. 7. Into the zone which constitutes the end of the second arm, 60a, and the intake point of the mixing screw of mixer 1, there are introduced as schematically represented by arrow 56, the other constituents of the mixture especially the binding agent and the hardening agent. These constituents are introduced continuously in suitable proportions which are a function of the rate of flow of delivered sand coming from belt 58a, then the mixture is formed inside the mixing device 1 and delivered in the active state, that is to say ready to harden, to exit 2. Said exit is located above a pneumatic accelerator 3 which, whatever the mode of execution chosen, has as its main function to violently project the mixture by jet 53 inside mold 5. To that end, from the exit of mixing device 1 to the exit of the pneumatic accelerator, the ready-to-harden mixture falls by simple gravity, then suddenly finds itself accelerated with force, in a vertical direction from top to bottom, when it is picked up by the current of gas under pressure introduced into the pneumatic accelerator by flexible duct 16.

The fourth embodiment of the installation, represented in FIG. 8, includes a chassis or frame directly under mixing device 1 which makes possible the mixing of all of the constituents. The ready-to-harden mixture falls from exit 2 of the mixing device into duct 57, and it is then successively carried by three conveyor belts 58, 58a and 58b, which move at high speed in tubular ducts 59, 59a, and 59b, and which are enclosed in the carriers 60, 60a, and 601) which form three articulated arms the ones with respect to the others in a horizontal plane. Deflectors, respectively 61, 61a and 61b cause the mixture to pass from the first to the second belt, from the second to the third belt and from the third belt to the pneumatic accelerator 3 placed at a right angle to the end of the third arm, below the latter. The mixture placed on the upper part of the third belt 58b is violently projected against deflector 61b then it flows by gravity inside the pneumatic accelerator 3, and finally it is picked up at the level of the latter by a gas current under high pressure which makes possible the distribution of the mixture in the form of a jet 53, narrow and perfectly calibrated, distributed at high speed, from top to bottom as indicated by arrow 6, from the exit of pneumatic accelerator 3 to the inside of mold 5.

Conveyor belt 58 guided inside tubular duct 59, is advantageously formed of an upper part placed inside said duct, and of a lower part placed externally to said duct (FIG. Rollers 62 placed at the ends of duct 59 insure the rapid displacement of the two parts. In addition to the fact that such a solution adapted for the transportation of the mixture proves advantageous since it is rapid, it is observed that the upper part of the belt is curvilinear while the lower part, of course, is flat. The upper part, depending on the rigidity of the material which constitutes the belt, either rests on bottom 59a of the duct, or is in contact with the latter only by its two longitudinal edges 63, so that a free space remains between bottom 59a of the duct and the lower face of the curvilinear upper part. Consequently, when the upper part of the conveyor belt reaches a point facing the downstream end of duct 59, it slackens and is subjected, for a few tenths of a second to torsion phenomena before it is taken back by downstream roller 62 and comes back to the upstream roller outside of duct 59. The particles of the mixture which might have had a tendency to stick on the upper part of the belt are then subjected, at the downstream end, to forces which naturally tend to loosen said particles and to release them from the belt to project them against the lower wall of the deflector.

The pneumatic accelerator of the installations in FIGS. 7 and 8 is advantageously made according to the following construction, represented in FIG. 9. A cylindrical body 63, the vertical axis of symmetry of which is 64, is welded to a horizontal flange 65 bolted on support 66 of deflector 61b. Support 66 and flange 65 both present a central opening through which the mixture which is carried at high speed by belt 58b flows freely as indicated by arrow 67, vertically from top to bottom, after its trajectory has been corrected by deflector 61b.

' A vertical tube 68, also welded to flange 65, forms inside body 63, facing the opening in the flange, a first guide for the mixture which already flows at a relatively high speed. Tube 68 is bevelled at its lower part and it forms a truncated cone zone 68a, the summit half angle of which is preferably less than 15. A slider member 69 is placed inside body 63, below said vertical tube 68, said slider member presenting at its upper part a truncated cone shaped boring 69a the summit half angle of which 8 of which 8 is identical with the one of the truncated cone shaped end of tube 68. Slider member 69 is guided with slight friction inside body 63 and is held and positioned inside the latter by means of a control rod 70 fitted with a handle 71 which runs through the lateral wall of body 63 and is fixed to slider member 69. A space 76, slanted with respect to the horizontal, disposed over part of the periphery of the lateral wall of body 63, simultaneously makes possible a rotation motion of the slider member inside body 63 and a vertical motion, from top to bottom or from bottom up, of said slider member inside the body. In that way, it is possible more or less to separate the upper truncated cone shaped end 69a of the slider member from the lower end 68a of the fixed tube 68. A neutral or active compressed gas, with respect to the mixture, is injected through duct 16 as far as a connection 72 located on the lateral wall of body 63. Connection 72 includes a horizontal axial duct 73 which opens into the cylindrical annular chamber 74 formed between body 63 on one side, tube 68 and a projecting part 75 of the slider member 69 on the other side. The gas under pressure then goes from chamber 74 into space which separates the ends 68a and 69a of tube 68 and of slider member 69, to enter into the internal part of the slider member in the form of a cone shaped annular jet downward convergent, the summit angle of which is equal to approximately 30. The mixture which falls from top to bottom between the internal walls of the slider of the pneumatic accelerator 3 is then picked up at the center of said jet of compressed gas, and taken at high speed, vertically from bottom up, inside mold 5 as schematically represented by arrow 6.

Of course, the play which remains between the slider and the tube is in direct relationship with the rate of flow of the compressed gas, and it is such that the pressure of gaseous fluid when it enters the slider in the form of a cone shaped annular jet, is greater than that of the same fluid circulating through duct 16 of intake. As an example, for the installation in FIG. 10 fitted with a mixing device 1, which delivers continuously at its exit 15 tons per hour of mixture, there is used a pneumatic accelerator 3 the slider member 69 of which has a height of 130 mm and internal diameter of mm. Tube 68 has a height of the order of 45 mm. For a vertical run of 5 mm of slider member 69 with respect to fixed tube 68, the play which exists between the ends 69a and 68a of the aforementioned members is 1 mm, the clearance 76 on the lateral wall of body 63, having a length of mm, and approximately occupying on body 63, on are of circle with a 45 summit angle.

The installations in FIGS. 1, 5 and 6, 7, 8 make possible distributions of mixtures which are not active yet to points of utilization distant 5 to 15 meters approximately from the end of mixing device 1 used for the mixing of the various constituents.

The invention is hereby claimed as follows:

1. Distribution apparatus for high speed projection of a granular and/or pulverulent mixture comprising a mixing device for the formation of the mixture, and means for picking up said mixture at the exit of the mix ing device and for its distribution as far as its point of utilization, said last named means comprising a pneumatic accelerator which communicates on one side with the exit of the mixing device and on the other side with the point of utilization of the mixture, first means for displacing the mixture from the exit of the mixing device to the intake of said pneumatic accelerator which at least in the zone terminating with the intake into the accelerator is vertical from top to bottom, and second means comprising a vertically disposed zone for taking the mixture from the interior of the accelerator while the mixture is still in movement from the first means and pneumatically forcing it from approximately the exit of the pneumatic accelerator to its point of utilization.

2. An apparatus as claimed in claim 1 wherein a tubular duct connects the exit of said pneumatic accelerator to the point of utilization of the mixture.

3. An apparatus as claimed in claim 1 wherein said pneumatic accelerator includes a body which communicates with the exit of said mixing device fitted with a venturi-shaped sleeve, in two parts: one internal part and an external part, placed so that the widened zone of the venturi is placed facing the exit of said mixing device, and the narrowed part of the venturi is placed facing the utilization point or the intake or a distribution duct, a radial channel running through the body and the external part of the venturi establishing communication between a source of gas under pressure and a cylindrical annular expansion chamber, which then becomes a truncated-cone, the wall of which is convergent toward the exit of said pneumatic accelerator, said chamber being located between said internal part and said external part of the venturi-forming sleeve and the internal part of said venturi and the intake of said distribution duct.

4. An apparatus as claimed in claim 1 wherein said pneumatic accelerator includes a cylindrical body the axis of symmetry of which is vertical, the lower opening of which is placed facing the point of utilization, and the upper opening of which faces the intake of mixture from the mixing device, said body guiding an internal slider member surmounted by a tube, said tube being bevelled in its lower part and forming a truncated-cone zone and said slider member presenting at its upper part a truncated-cone shaped boring the half summit angle of which is identical with the truncated-cone end of the tube, a cylindrical annular chamber formed between said body, said tube and a projection of said slider member, a transverse opening running through said body to said chamber, said chamber extending between the two truncated-cone faces of the tube and of the slider member which face each other, in the form of a truncated-cone shaped annular passageway with walls converging toward the exit of the pneumatic accelerator.

5. An apparatus as claimed in claim 4 comprising means to adjust the play which exists between the truncated-cone shaped faces which face each other of said tube and of said slider member, and which define the truncated-cone shaped annular ring through which the carrying gas under pressure is introduced into the central part of the pneumatic accelerator, said means being operable from the outside of said accelerator.

6. An apparatus as claimed in claim 4 wherein said truncated-cone shaped annular passageway formed between said tube and said slider member forms a jet which is cone shaped and annular, converging toward the exit of the accelerator, the summit angle of which is approximately equal to 30.

7. An apparatus as claimed in claim 1 wherein there is inserted between the exit of the mixing device and the intake point of the pneumatic accelerator a chamber and a plurality of valves each with a deformable internal sleeve, including an upper and lower valve in said chamber, respectively communicating with the exit of the mixing device and the intake point of the pneumatic accelerator, and means to simultaneously control the opening of one of the two valves and the closing of the other valve.

8. An apparatus as claimed in claim 1 comprising a tubular distribution duct containing a conveyor belt to which there is impressed a fast longitudinal displacement motion, the upper part of said conveyor belt being placed inside said duct, and the lower part being placed on the outside of, and below, said duct.

9. Apparatus as claimed in claim 1 comprising means to prevent any reflux of the mixture from said accelerator toward the mixing device.

10. Apparatus as claimed in claim 1 wherein said mixture falls by gravity in said first means and its movement in said second means is pneumatically accelerated by compressed air.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTION PATENT N0. 3,912,238 DATED October 14, 1975 |NV ENTOR(S) I GERARD YVES RICHARD It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below: Column 14, line 9, delete "of which 8 after 8 Column 15, line 28, "or", second occurrence, should read -of- Signed and Sealed this I Twenty-first Day Of December 1976 [SEAL] Arrest:

RUTH c. MASON c. MARSHALL DANN Arresting Officer Commissioner oj'latenls and Trademarks 

1. Distribution apparatus for high speed projection of a granular and/or pulverulent mixture comprising a mixing device for the formation of the mixture, and means for picking up said mixture at the exit of the mixing device and for its distribution as far as its point of utilization, said last named means comprising a pneumatic accelerator which communicates on one side with the exit of the mixing device and on the other side with the point of utilization of the mixture, first means for displacing the mixture from the exit of the mixing device to the intake of said pneumatic accelerator which at least in the zone terminating with the intake into the accelerator is vertical from top to bottom, and second means comprising a vertically disposed zone for taking the mixture from the interior of the accelerator while the mixture is still in movement from the first means and pneumatically forcing it from approximately the exit of the pneumatic accelerator to its point of utilization.
 2. An apparatus as claimed in claim 1 wherein a tubular duct connects the exit of said pneumatic accelerator to the point of utilization of the mixture.
 3. An apparatus as claimed in claim 1 wherein said pneumatic aCcelerator includes a body which communicates with the exit of said mixing device fitted with a venturi-shaped sleeve, in two parts: one internal part and an external part, placed so that the widened zone of the venturi is placed facing the exit of said mixing device, and the narrowed part of the venturi is placed facing the utilization point or the intake or a distribution duct, a radial channel running through the body and the external part of the venturi establishing communication between a source of gas under pressure and a cylindrical annular expansion chamber, which then becomes a truncated-cone, the wall of which is convergent toward the exit of said pneumatic accelerator, said chamber being located between said internal part and said external part of the venturi-forming sleeve and the internal part of said venturi and the intake of said distribution duct.
 4. An apparatus as claimed in claim 1 wherein said pneumatic accelerator includes a cylindrical body the axis of symmetry of which is vertical, the lower opening of which is placed facing the point of utilization, and the upper opening of which faces the intake of mixture from the mixing device, said body guiding an internal slider member surmounted by a tube, said tube being bevelled in its lower part and forming a truncated-cone zone and said slider member presenting at its upper part a truncated-cone shaped boring the half summit angle of which is identical with the truncated-cone end of the tube, a cylindrical annular chamber formed between said body, said tube and a projection of said slider member, a transverse opening running through said body to said chamber, said chamber extending between the two truncated-cone faces of the tube and of the slider member which face each other, in the form of a truncated-cone shaped annular passageway with walls converging toward the exit of the pneumatic accelerator.
 5. An apparatus as claimed in claim 4 comprising means to adjust the play which exists between the truncated-cone shaped faces which face each other of said tube and of said slider member, and which define the truncated-cone shaped annular ring through which the carrying gas under pressure is introduced into the central part of the pneumatic accelerator, said means being operable from the outside of said accelerator.
 6. An apparatus as claimed in claim 4 wherein said truncated-cone shaped annular passageway formed between said tube and said slider member forms a jet which is cone shaped and annular, converging toward the exit of the accelerator, the summit angle of which is approximately equal to 30*.
 7. An apparatus as claimed in claim 1 wherein there is inserted between the exit of the mixing device and the intake point of the pneumatic accelerator a chamber and a plurality of valves each with a deformable internal sleeve, including an upper and lower valve in said chamber, respectively communicating with the exit of the mixing device and the intake point of the pneumatic accelerator, and means to simultaneously control the opening of one of the two valves and the closing of the other valve.
 8. An apparatus as claimed in claim 1 comprising a tubular distribution duct containing a conveyor belt to which there is impressed a fast longitudinal displacement motion, the upper part of said conveyor belt being placed inside said duct, and the lower part being placed on the outside of, and below, said duct.
 9. Apparatus as claimed in claim 1 comprising means to prevent any reflux of the mixture from said accelerator toward the mixing device.
 10. Apparatus as claimed in claim 1 wherein said mixture falls by gravity in said first means and its movement in said second means is pneumatically accelerated by compressed air. 